The primary thrust of the project is to develop a better understanding of the molecular (biochemical) and physiological processes inportant for implantation and normal early development. Special emphasis is placed on coordinate development and interactions which occur between the embryo and its uterine environment to achieve implantation. Specifically, this includes: examination of proteinase activities in blastocysts and uterine fluid and their regulation; protein synthesis in blastocysts and its control by hormones and the uterine environment; the interaction between endometrial fluid and antitrophoblastic agents; and the scanning electron microscopical structure of blastocyst-uterine relations.